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Pretransplant nutritional conditioning (PNC) of transplants during greenhouse production may improve recovery from transplanting stress and enhance earliness and yield of watermelon [Citrullus lanatus (Thumb.) Matsum. & Nakai]. Two greenhouse experiments (Expts. 1 and 2) and field experiments in South Carolina and North Carolina (Expt. 3) were conducted to evaluate N and P PNC effects on watermelon seedling growth and their effects on fruit yield and quality. `Queen of Hearts' triploid and `Crimson Sweet' diploid watermelon seedlings were fertilized with N from calcium nitrate at 25, 75, or 225 mg·liter–1 and P from calcium phosphate at 5, 15, or 45 mg·liter–1. In the greenhouse, most variation in the shoot fresh and dry weights, leaf count, leaf area, transplant height, and root dry weight in `Queen of Hearts' and `Crimson Sweet' was attributed to N. Cultivar interacted with N, affecting all seedling growth variables, but not leaf area in Expt. 2. To a lesser extent, in Expt. 1, but not in Expt. 2, P interacted with cultivar, N, or cultivar × N and affected shoot fresh and dry weights, leaf count and leaf area. In the field, transplant shock increased linearly with N, regardless of cultivar or field location. The effect of PNC on plant growth diminished as the growing season progressed. For both cultivars at both locations, N and P PNC did not affect time to first staminate flower, fruit set, fruit width or length, soluble solids concentration, or yield. Vining at Charleston for both cultivars was 2 days earlier when N was at 75 rather than 25 mg·liter–1, without further change with the high N rate. At Clinton, the first pistillate flower was delayed linearly the higher the N rate for `Crimson Sweet'. At Charleston, hollow heart in the `Queen of Hearts' increased nearly 3 times when N PNC rate was tripled (from 75 or 225 mg·liter–1), while N had no effect on hollow heart in `Crimson Sweet'. In contrast, at Clinton, hollow heart in either cultivar was affected by P PNC, not N. PNC with 25N–5P (in mg·liter–1) can be used to reduce seedling growth and produce a more compact plant for easier handling, yet not reduce fruit quality or yield.

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Cucumber (Cucumis sativus L.) and horned cucumber (C. metuliferus Naud.) germplasm were evaluated for their resistance to root-knot nematodes (Meloidogyne spp.). All 24 C. metuliferus cultigens evaluated were resistant to all root-knot nematodes tested-M. incognita (Kofoid and White) Chitwood race 3, M. arenaria (Neal) Chitwood race 2, and M. hapla Chitwood. All 884 C. sativus cultigens (cultivars, breeding lines, and plant introduction accessions) tested were resistant to M. hapla and few to M. incognita race 3. Only 50 of 884 C. sativus cultigens evaluated were somewhat resistant to M. arenaria race 2 and M. incognita race 3. A retest of the most resistant C. sativus cultigens revealed that LJ 90430 [an accession of C. sativus var. hardwickii (R.) Alef.] and `Mincu' were the only cultigens that were moderately resistant to M. arenaria race 2. LJ 90430 was the only cultigen, besides the two retested C. metuliferus cultigens, that was resistant to M. javanica (Treub) Chitwood. All C. sativus cultigens retested, including LJ 90430, were highly susceptible to M. incognita races 1 and 3. The two C. metuliferus cultigens retested were highly resistant to all root-knot nematodes tested-M. arenaria race 2, M. incognita races 1 and 3, and M. javanica.

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, cucurbit PM is generally considered one of the most important diseases of cucurbits ( Zitter et al., 1996 ) and poses a serious constraint to the production of pumpkins in Kentucky. Cucurbit PM can affect leaves, petioles, and stems with tissue turning

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Yellow and zucchini squash (Cucurbita pepo L.) cultigens (breeding lines and cultivars) were evaluated over a 2-year (1995 and 1996) period in North Carolina. Yellow squash cultigens that performed well (based on total marketable yields) were `Destiny III', `Freedom III', `Multipik', XPHT 1815, and `Liberator III' in Fall 1995 and HMX 4716, `Superpik', PSX 391, `Monet', `Dixie', XPH 1780, and `Picasso' in Spring 1996. Some of the yellow squash cultigens evaluated had superior viral resistance: XPHT 1815, XPHT 1817, `Freedom III', `Destiny III', `Freedom II', TW 941121, `Prelude II', and `Liberator III' in Fall 1995 and XPHT 1815, `Liberator III', `Prelude II', and `Destiny III' in Fall 1996; all these cultigens were transgenic. The yellow squash cultigens that performed well (based on total marketable yields) in the Fall 1995 test had transgenic virus resistance (`Destiny III', `Freedom III', XPHT 1815, and `Liberator III') or had the Py gene present in its genetic background (`Multipik'). Based on total marketable yields, the best zucchini cultigens were XPHT 1800, `Tigress', XPHT 1814, `Dividend' (ZS 19), `Elite', and `Noblesse' in Fall 1995; and `Leonardo', `Tigress', `Hurricane', `Elite', and `Noblesse' in Spring 1996. The zucchini cultigens with virus resistance were TW 940966, XPHT 1814, and XPHT 1800 in Fall 1995 and XPHT 1800, XPHT 1776, XPHT 1777, XPHT 1814, and XPHT 1784 in Fall 1996. Even though TW 940966 had a high level of resistance in the Fall 1995 test, it was not as high yielding as some of the more susceptible lines. Viruses detected in the field were papaya ringspot virus (PRSV) and watermelon mosaic virus (WMV) for Fall 1995; while PRSV, zucchini yellow mosaic virus (ZYMV), and WMV were detected for Fall 1996. Summer squash cultigens transgenic for WMV and ZYMV have potential to improve yield, especially during the fall when viruses are more prevalent. Most transgenic cultigens do not possess resistance to PRSV, except XPHT 1815 and XPHT 1817. Papaya ringspot virus was present in the squash tests during the fall of both years. Thus, PRSV resistance must be transferred to the transgenic cultigens before summer squash can be grown during the fall season without the risk of yield loss due to viruses.

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The oomycete plant pathogen Phytophthora capsici Leonian affects the cucurbit industry annually, in some cases causing 90% to 100% crop loss ( Babadoost, 2000 ; Meyer and Hausbeck, 2012 ). Michigan is a leading producer of processing squash

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Muskmelon ( Cucumis melo ), squash ( Cucurbita sp.), cucumber ( Cucumis sativa ), pumpkin ( Cucurbita pepo ), and other cucurbit crops are valued at more than $1.6 billion per year in the United States ( U.S. Department of Agriculture, 2017

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Zucchini yellow mosaic virus (ZYMV), a member of the genus Potyvirus in the family Potyviridae , infects cucurbits worldwide. Plants infected with ZYMV develop blistering and malformed leaves. The disease can reduce fruit yield and quality

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powdery mildew in cucurbit crops in the United States ( Zitter et al., 1996 ). These pathogens can move long distances within the growing season, from southern to northern U.S. production areas ( Zitter et al., 1996 ). Cucurbit powdery mildew infects

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mildew in cucurbits. These organisms differ in virulence against cucurbit species and in their sensitivity to fungicides ( Lebeda et al., 2008 ). Presently, there are at least seven pathogenically distinct races of P. xanthii and these are

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Cucurbit powdery mildew (CPM) is a common and serious disease of melon worldwide. CPM infection acts as a sink for photosynthates from the leaves, which leads to premature loss of foliage and, subsequently, to loss of fruit quality and yield

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